Xigmatek continues the new trend of 'heatpipe stacking' with its latest heatsink, the SD128264 Aegir. The Aegir is an exposed heatpipe base tower heatsink made to accommodate one or two 120mm fans. A single 120mm 2200-1000RPM PWM fan is supplied with it, and judging by the excellent thermal test results there's really no need for a second... unless you're planning on operating both fans at the slowest possible speeds.